Stoker-blower control mechanism



April 17, 1928. 1,666,510

H. F. SCHMIDT STOKER BLOWER CONTROL MECHANISM Filed Feb. 18, 1921 Henry Edie/[midi INVENTOR ATTORNEY Patented Apr. 17, 1928.

UNITED STATES PATENT OFFICE.

HENRY F. SCHMIDT, OF SWARTHMORE, PENNSYLVANIA, ASSIGN OR TO WESTING- HOUSE ELECTRIC 1) MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VAN IA.

STOKER-IBLOWER CONTROL MECHANISM.

Application filed February 18, 1921. Serial No. 446,148.

My invention relates to furnaces and more particularly to devices for controlling its operation, and it has for an object to provide an improved and eflicient arrangement for efiectively "controlling the operation of an air fan associated with the furnace."

Another object is to provide an improved pressure-responsive apparatus for controlling the operation of an an fan.

Another object is to provide pressure-responsive apparatus for controlling the operation of an air fan which is responsive. to a pressure derived from the flow of air to said fan.

Still another object is to provide an apparatus for controlling the operation of an air fan which is controlled by a pressure derived from either steam flow or feed water flow, and the flow of air to said fan.

These and other objects are effected by my invention, as will be apparent from the following description and claims taken in connection with the accompanyin drawings, forming a part of this app ication, in which Fig. 1 is a diagrammatic view, partially in section, of an apparatus embodying my invention; and

Fig. 2 is a diagrammatic illustration of the "apparatus shown in Fig. 1 applied to a steam generatori' In the operation of power plants having stoker furnaces, regulating means must be provided for the fuel-feeding and draft-producing apparatus which shall be responsive to the requirements of the prime movers for steam. Arrangements of Pitot tubes and Venturi elements have been installed in the steam mains, leading from the boilers; to oocordance with the steam requirements placed Referring to the drawing for a more detailed description of my invention, 10 indicates a Venturi element located in a conduit 11 communicating with the boiler. As pointed out above, the conduit 11 may be either a steam main or a feed-water line or main. The throat of the Venturi elemelit is connected by means of a conduit 12 with a chamber 13 of a diaphragm motor 14.- The conduit 11 near the entrance to the Venturi element communicates through aconduit 15 with a chamber 16 of the diaphragm motor14. A diaphragm 17 of the motor ma be of any suitable construction. The diap ragm 17 of the motor is moved in one direction or the other in accordance with variations of the pressure due to the changes in the rate of flow through the conduit 11 in a manner well understood by those skilled inthis art. The diaphragm 17 is connected by a link 18 to one end of a rocker arm 19. The other end of this rocker arm is connected to a link 20 which in turn is attached to the diaphragm 21 of a diaphragm motor 22. The diaphragm motor 22 is separatedinto two chambers 22 and 23 by the diaphragm 21. The chamber 22' is subject to the pressure of the atmosphere and the chamber 23 communicates through a conduit 24 with a blower casing 25 at the point of lowest absolute pressure when a propeller 26 of the blower is rotating. The propeller 26 is driven through a shaft 27 by means of a turbine 28 or similar drive means, A valve 29, located in a conduit 30 supplying motive fluid to the turbine, is adapted to be controlled by a piston 31 located in a cylinder 32 and connected to the valve b means of a rod 33. A chamber 34 above t e piston 31 communicates with a cylinder 35 o a relay mechanism throu h a conduit 36', and a chamber 37 below t e piston 31 communicates -with the cylinder 35 through a conduit 38. Conduits 39 and 40 lead into the cylinder from a suitable sup ply of fluid under pressure and a conduit 41 leading from the cylinder 35 serves as an exhaust for the pressure fluid. Mounted in the cylinder 35 are four pistons, 42, 43, 44 and 45 which are connected to a rod 46 which in turn forms a pivot'for the rocker arrn 19.

In Fig. 2 I show the apparatus. described and illustrated in Fig. 1 arranged in a boiler installation. The conduit 11 connects to a boiler 50 under which is placed a stoker furnace 51, fuel-feeding mechanism 52 of any desired type is. employed tosupply fuel to the furnace. The apparatus herein shown may be readily operated by a flow of steam or of feed water through the conduit 11, each of which are indicative of the boiler requirements for steam.

The blower casing 25 connects with an air duct 53 which enters the furnace 51 through an opening 54 beneath the same.

Having thus described an apparatus constructed in accordance with my invention, the operation is as follows: When the velocity of the fluid and consequently its volume, passing through the conduit 11 increases, the pressure at the throat of the Venturi element drops, producing a corresponding drop in the pressure in-the chamber 13 of the diaphragm motor 14. The

diaphra m 17 then moves upwardly and causes t e pistons 43 and 44 to move upwardly and to uncover the ends of the conduits 36 and 38 respectively, leading to, the

cylinder 35. Fluid under pressure,'preferably oil, from the conduit 40 then enters the conduit. 38 and the chamber 37 below the piston 31 and some of the pressure fluid in the oil chamber 34 above. the piston is pe r-. mitted to escape to the exhaust 41. This in-' creased pressure thus brought to bear on the lower side of the piston 31 forces the piston 31 up, thus tending to open wider the valve 29 in the conduit 30. supplying steam to the turbine 28. The speed of the blower 26 and the velocity of the air passing through the casing 25 are then increased, causing a decreased pressure in the conduit 24 and in the chamber 23 which causes the diphi'agm 21 in the motor 22 to fall, the atmospheric pressure above the diaphragm 21 remaining conincrease of stant. This downward movement of thediaphragm 21 acting through the link 20, roc er arm 19, and rod 46 produces a proportional downward movement of the pistons 43 and 44, closing the end of the conduits 36 and 38 and thereby restoring equilibrium in the relay mechanism.

Similarly, when the volume of fluid passing through the pipe line 11 decreases, the

.pressure at the throat of the Venturi "ele ment increases, producing a corresponding pressure in -t e chamber 13 of the diaphragm motor 14. This change of pressure within the chambers of the diaphragm motor 14 produces .a downward movement of thddiaphragm 17, which, acting through the link 18, lever 19, and rod 46, causes the pistons 43 and 44 to move downwardly and to uncover the ends of the conduits 36 and 38 respectively. Fluid under pressure from conduit 39 will then enter the passage 36 and the. chamber 34 above the piston 31 and some of the pressure fluid beneath the piston 31 will be permitted to escape to the exhaust conduit 41. The increased pressure thus brought to bear on the upper side of the piston 31 forces the piston down, tending to close the valve 29 in the conduit, 30 sup lying steam to the turbine 38. The speed of the blower and consequently the velocity of the air passing therethrough' are then decreased, resulting in an increase in pressure in the conduit 24 and the chamber 23. This increased pressure allows a return upward movement of the diaphra m 21 which, acting through the link 20, me er arm 19 and rod 46, causes an upward movement of the pistons 43 and 44 and closes the conduits'36 and 38, thereby msm.

On the other hand, variation in the velocity of the flow of air to the furnace reacts through the relay mechanism to establish a uniform speed of the blower thus delivering a uniform air supply. The varying conditions of air are conversely due to the resistance to the fiow of air through the fuel bed. A heavy fuel bed retards the passage of air therethrough and as a result the velocity of air. through the blower is diminished. The diminution of air velocity causes a decrease in suction at the throat oftube 24 and the pressure increases in the tube 24 and chamber 23 and thus raises the disc which will react to raise the fluid piston 46 and cause an increased flow of air to the furnace. The pressure motor 14 and 22 are constructed to give a uniform regulation of air supply to the furnace over a wide range of requlre- I ments.

While it is to be understood that other well known mechanisms for operating 1n accordance with the volume of the fluid passing through the pipe line 11 by means of pressure differences may be employed, as for example a Pitot tube; the Venturi element is particularly adapted for use with a fan the rate of flow through each of these 1 ed for rotation in the throat portion of a converging-diverging passage of the fan housing 25. It is to be observed, however, that my invention in certain of its broader aspects is not limited to this particular type of fan and housing, for it might equally as well be applied to any type of fan having a housing which is provided with a constricted inlet opening for supplying air to said fan. By constricted inlet opening I mean constricted with relation to the space within which the fan is positioned.

' .While I have shown my invention in but lating eflect derivable cation to said control means ciated with the boiler,

one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various other changes and modifications without departing from the spirit thereof and I desire. therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. In a relay heat regulating mechanism for boiler furnaces, a conduit communicating with the boiler, an air supply device and means cooperatively associated with the conduit and air supply device for controlling the speed of said air supply device by a re u- 0th from the velocity of fluid flowing through the conduit and from the velocity of air supply.

2. In combination with a boiler furnace rovlded with air suppl means and fluid deivery means, of contro means operable for ad ustmen t of the rate of air supply, means for deriving a primary controlling force which is a function of the rate of fluid passmg through the delivery means, additional means for deriving a secondary controlling force which is a function of the rate of air passing to the furnace and means for coinbining said forces diflerentially for application to said control means.

3. In combination with a stoker furnace provided with air supplying means and fluid supply means, of control means operable for the adjustment of the rate of air supply, means for deriving a controlling force which is substantiall proportional to a function of the rate of air su ply to said furnace, additional means for geriv force which is substantiall proportional to a function of the rate of fluid supply assoand means for combining said forces differentially for appliing a controlling 4. In a stokerfurnaoe mechanism for vapor generators, the combination of a fluid delivery main, a blower for supplying air to the generator, a motor to drive the blower and means for controlling the speed of the motor responsive to the velocit of the air passing through the blower an velocity of fluid assing through the main.

5. 121 a boiler furnace having a stoker and a fluid delivery conduit connected to the boiler, the combination of a blower for delivering air to the furnace, a relay mechanism connected to the fluid conduit and the blower for controlling the speed of the blower, said mechanism comprisin a diaphragm motor actuated by the ve ocity of fluid flowing through the conduit, a second diaphragm motor actuated by the velocity of air through the blower and a means associated with said diaphragm motors whereby the velocity of air delivered by the blower is directly proportional to the velocity of fluid through the conduit.

6. In a boiler furnace having a stoker and -a fluid supply main connected to the boiler, an air supply means for the furnace, a regulating device for the air supply means comprising a diaphragm motor actuated by the velocity of fluid passing through the main, a second diaphragm motor actuated by the velocity of air passing through the air sup-- ply means, connecting means between said motors and means associated w th said connecting means whereby the rate of air assing through the blower is a function o the rate of fluid a'ssing throu h the conduit.

7. In a relay heat mec anism for boiler furnaces, a conduit communicating with the boiler, an air su ply device and means cooperatively associated withthe conduit and air supply device for controlling the rate of air supply to the furnace b a regulatin effect derivable both from ve ocity of flui flow through the conduit and the pressure in said air su ply device.

8. Thecom ination with a furnace, of a housing defining a converging-diverging passage, a ropeller type fan mounted coaxially oft e housing and within the throat portion thereof, pressure responsive means for regulating the speed of the fan, conduit means connecting the throat portion of the housin with the pressure responsive means, and 0t er conduit means forconveying air from the housing to the furnace.

9. In an air supply means for a furnace, a housing definin a converging-diver ing passa e, a propel or type fan mounte in the t oat of V the passage and coaxially thereof, driving means for the fan means responsive to ressure for controlling the speed of the driving means, and conduit means connecting'the throat portion of the assae with the pressure responsive means or a acting the operation of the latter 10. In combination with a furnace, :5 fan, si've means, and other conduit means for cona housing enclosing said fan and having a. veililng air from the housing to the furnace. constricted inlet opening for supplying air .testimony whereof, I'have hereunto to said fan, pressure-responsive means for subscribed my name this 31st day of Janu- 5 regulating the speed of the fan, conduit ary, 1921.

means connecting the constricted inlet opening in the housing with the pressure-respon- HENRY F. SCHMIDT. 

